Oven for cooking food

ABSTRACT

An oven for cooking food, the oven comprising:
         an enclosure ( 2 ) for receiving the food to be heated and for containing a cooking atmosphere, the enclosure ( 2 ) comprising two horizontal walls forming respectively a bottom wall ( 9 ) and a top wall ( 10 ), interconnected by at least two vertical side walls ( 7, 8 ), the enclosure ( 2 ) being closed by at least one door ( 5 ) that is likewise vertical, and communicating with the outside via an exhaust opening ( 28 ) for exhausting gas inside the enclosure ( 2 ) and at a pressure above atmospheric pressure; and   a heater device ( 11 ) for heating the cooking atmosphere.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/540,347, filed Jun. 21, 2005, which was a national phase filing ofPCT/EP03/15037, filed Dec. 23, 2003.

The present invention relates to ovens for cooking food.

More particularly, the invention relates to an oven comprising:

-   -   an enclosure for receiving the food to be heated and for        containing a cooking atmosphere, the enclosure comprising two        horizontal walls forming respectively a bottom wall and a top        wall, interconnected by at least two vertical side walls, the        enclosure being closed by at least one door that is likewise        vertical, and    -   a heater device for heating the cooking atmosphere.

One aim of the invention is to improve this kind of ovens.

According to an embodiment of the invention, is an oven for cookingfood, comprising:

-   -   an enclosure for receiving the food to be heated and for        containing a cooking atmosphere, the enclosure comprising two        horizontal walls forming respectively a bottom wall and a top        wall, interconnected by at least two vertical side walls, the        enclosure being closed by at least one door that is likewise        vertical, and communicating with the outside via an exhaust        opening for exhausting gas inside the enclosure and at a        pressure above atmospheric pressure; and    -   a heater device for heating the cooking atmosphere;

the oven being characterized by the fact that it comprises:

-   -   a regulation chamber, filled at least in part with a liquid of        volume adapted to vary between a high level and a low level, the        regulation chamber communicating with the enclosure via an air        inlet; and    -   an admission duct which extends between a high end and a low        end, the high end opening out outside the regulation chamber and        the enclosure, and the low end being closed by the liquid when        the level of the liquid corresponds substantially to its high        level.

Prior art ovens are known in which pressure inside the enclosure canrise, for example when vapour is produced or when the door is closed orwhen the heater device is a gas burner (production of combustion gasesor extra pressure on lighting), and this rise in pressure can be ofgreater or lesser magnitude and can exist for a greater or lesser lengthof time. For obvious safety reasons, such pressure rises need to begoverned, kept down, and even eliminated. In prior art ovens, this isgenerally done by means of an opening provided with a mechanical flap.

That type of flap needs regular maintenance since otherwise it runs therisk of no longer operating properly, particularly when it becomesclogged. Its safety function is then no longer performed in a mannerthat is effective and reliable.

That drawback is mitigated by the embodiment of the invention abovedefined.

Indeed, it enables pressure rises in the enclosure to be governed:

-   -   in a manner that is not mechanical, thus making it possible to        overcome constraints associated with the maintenance required by        prior art ovens;    -   in a manner which is adjustable since it is possible to stop gas        coming from the enclosure or to allow it to pass to a greater or        lesser extent by modifying the level of the liquid; and    -   in a manner that is reliable since with a liquid there is no        danger of unwanted closure or mechanical blocking, and even if        the bottom end of the admission duct dips below the high level        of the water, should the pressure rise excessively, then the gas        can push back the water, “bubble through”, and escape via the        admission duct.

Recourse may optionally also be had to one or more of the followingdispositions:

-   -   the oven includes an evacuation chamber filled at least in part        with a liquid of volume that is adapted to vary between a high        level and a low level, said evacuation chamber communicating        with the regulation chamber;    -   the oven includes an evacuation tube extending between the        exhaust opening and a high end opening out into the evacuation        chamber above the high and low liquid levels;    -   the oven includes a chimney extending between a first end        communicating with the outside of the evacuation chamber and a        second end coming over the high level of the liquid, said second        end allowing gas under positive pressure to escape from the        enclosure via the evacuation tube;    -   the oven includes a regulator itself comprising the regulation        chamber and the evacuation chamber, these two chambers        constituting volumes that are separated from each other at least        in part and that communicate with each other via a narrow        passage adapted to allow the liquid to flow between these two        chambers;    -   the oven includes, in the evacuation chamber, a first        temperature probe for measuring the temperature of the gas        coming from the exhaust opening, and in the regulation chamber,        a second temperature probe for measuring the temperature of the        gas coming into the enclosure via the air inlet;    -   the oven includes, in the evacuation chamber, a first        temperature probe for measuring the temperature of the gas        coming from the exhaust opening, and a second temperature probe        placed below the low level of the liquid in the evacuation        chamber;    -   the oven includes calculation means for determining the relative        humidity in the oven as a function of the temperatures measured        by the first and second probes;    -   the oven includes a fan disposed inside the enclosure to stir        the cooking atmosphere heated by the heater device, said fan        creating a suction zone inside the enclosure, the air inlet        being situated substantially in the suction zone of the fan;    -   the oven includes vapour-producing means suitable for delivering        water vapour into the enclosure;    -   the exhaust opening for exhausting gas under positive pressure        inside the enclosure is situated beneath the heater device;    -   the exhaust opening opens out substantially in the lowest point        of the bottom wall; and    -   the exhaust opening communicates with a siphon adapted to        evacuate liquids and condensates from the enclosure while        preventing cold air from rising into the enclosure.

According to another embodiment of the invention, is an oven for cookingfood, comprising:

-   -   an enclosure for receiving the food to be heated and for        containing a cooking atmosphere, this enclosure comprising two        horizontal walls, respectively forming a bottom wall and a top        wall, interconnected by at least two vertical side walls, this        enclosure being closed by at least one door which is also        vertical, and communicating with the outside by means of an        evacuation aperture for gases under positive pressure in the        enclosure.

This oven further comprises a first temperature probe to measure thetemperature of the gases issuing from the evacuation aperture.

Prior art ovens are known possibly comprising means for the productionof steam arranged to supply steam in the enclosure. These prior artovens have the drawback to not allow a reliable control of the humidityin the enclosure. Particularly, these prior art ovens usually do nottake into account the humidity produced by the food itself.

That drawback is mitigated by the embodiment of the invention abovedefined.

Indeed, thanks to these dispositions, it is possible to calculate thehumidity rate in the enclosure from the temperature measured with thefirst probe and from pre-recorded graphs. The cooking is then adjustedto the humidity rate calculated in this way.

Recourse may optionally also he had to one or more of the followingdispositions:

-   -   the oven comprises calculating means of calculating the humidity        rates in the oven as a function of the temperature measured at        the first probe;    -   the oven comprises a second temperature probe to measure a        reference temperature;    -   the oven, wherein the humidity rates in the oven, is calculated        by the calculating means as a function of the temperature        measured at the first and second probes;    -   the oven comprises a heater for heating the cooking atmosphere;    -   the oven comprises a fan, located in the interior of the        enclosure, to stir the cooking atmosphere heated by the heater,        this fan creating an area of low pressure in the enclosure, and    -   the oven comprises an air inlet opening in the enclosure,        approximately in said low-pressure area of the fan; thanks to        this disposition, it is possible to allow air to enter in the        enclosure in order to dry the atmosphere in it, in particular at        the end of the cooking process; it is possible, for instance, to        make food more crunchy; thanks to this disposition, it is also        possible to let air go into the enclosure to cool down more        quickly the cooking atmosphere, if it appears necessary in a        cooking cycle; this disposition also allows to stir with the fan        the cool air entering into the enclosure, as soon as it flows        through the air inlet; this is an advantage with regard to ovens        in which the cool air enters from the top or the bottom of the        enclosure and respectively cool down the top or bottom trays;        thanks to this embodiment of the invention, it is then possible        to reach in the enclosure a temperature more homogeneous;    -   the oven comprises a regulation chamber, at least partially        filled with a liquid of which the volume is adjusted so as to        vary between a high level and a low level, this regulation        chamber communicating with the air inlet;    -   the oven comprises an admission duct which extends between a        high end and a low end, the high end opening outside the        regulation chamber and the enclosure, and the low end being        covered by the liquid when the level of the liquid corresponds        approximately to its high level;    -   the oven comprises an evacuation chamber, at least partially        filled with a liquid of volume adapted to vary between the high        level and the low level, this evacuation chamber communicating        with the regulation chamber;    -   the oven comprises a regulation box, itself comprising the        regulation chamber and the evacuation chamber, these two        chambers constituting volumes which are at least partially        separated from one another, communicating between one another by        means of a passage of limited size, designed such as to allow        the liquid to circulate between these chambers;    -   the oven comprises an evacuation tube extending between the        evacuation aperture and a high end, opening into the evacuation        chamber above the high and low levels of the liquid;    -   the oven comprises a chimney extending between a first end        communicating with the outside of the evacuation chamber and a        second end entering above the high level of the liquid, this        second end allowing the gases under overpressure in the        enclosure to escape via the evacuation tube;    -   the second temperature probe is located beneath the low level of        the liquid in the regulation box;    -   the first temperature probe is located above the high level of        the liquid in the evacuation chamber;    -   the oven comprises means for the production of steam, arranged        to supply steam in the enclosure.

According to another embodiment of the invention, is an oven for cookingfood, comprising:

-   -   an enclosure intended to accommodate the food to be heated and        containing a cooking atmosphere, this enclosure comprising two        horizontal walls, respectively forming a bottom wall and a top        wall connected by at least two vertical side walls, this        enclosure being closed by at least one door which is also        vertical, and communicating with the outside by means of an        evacuation aperture for gases under positive pressure in the        enclosure, and    -   a heater device for heating the cooking atmosphere.

Further, in this oven the evacuation aperture for gases under positivepressure in the enclosure is located beneath the heater device.

Prior art ovens are known possibly comprising an evacuation aperture tocontrol the evacuation of gases under positive pressure in theenclosure. These gases are for instance constituted of humidity from theenclosure produced by the cooked food and/or by vapour producing meansand/or by the combustion gases, when the heater device is a gas burner.

The above defined embodiment of the invention allows improving thehomogeneity of the heat distribution in this kind of oven.

Indeed, with this disposition it is possible to limit, and even tocancel, the flue action from the chimney with which the evacuationaperture communicates, while allowing the gases even under a smallpositive pressure in the enclosure to escape freely from the enclosure,without using a valve, a vent or any other mechanical device, which canbe blocked, or even without siphon. The temperature difference betweenthe top and the bottom of the oven is reduced and the heat distributionin the enclosure is more homogeneous.

Recourse may optionally also be had to one or more of the followingdispositions:

-   -   the evacuation aperture opens at the level of the point which is        approximately the lowest point of the bottom wall;    -   the evacuation aperture communicates with a siphon arranged to        evacuate liquids and condensates from the enclosure while        avoiding cool air upwelling in the enclosure;    -   the oven comprises means for the production of steam, designed        to provide steam in the enclosure;    -   the oven comprises a fan, located in the interior of the        enclosure, to stir the cooking atmosphere heated by the heater        device, this fan creating an area of low pressure in the        enclosure;    -   the oven comprises an air inlet in the enclosure, located        approximately in said area of low pressure of the fan;    -   the oven comprises a regulation chamber, filled at least in part        by liquid of which the volume is adjusted so as to vary between        a high level and a low level, this regulation chamber        communicating with the air inlet;    -   the oven comprises an admission duct which extends between a        high end and a low end, the high end opening outside the        regulation chamber and the enclosure, and the low end being        covered by the liquid when the level of the liquid corresponds        approximately to its high level;    -   the oven comprises an evacuation chamber, filled at least in        part by a liquid of which the volume is adjusted so as to vary        between the high level and the low level, this evacuation        chamber communicating with the regulation chamber;    -   the oven comprises the regulation chamber and the evacuation        chamber, these two chambers constituting volumes which are at        least partially separated from one another, communicating        between one another by means of a narrow passage, adapted to        allow the liquid to flow between these chambers;    -   the oven comprises an evacuation tube extending between the        evacuation aperture and a high end, opening into the evacuation        chamber above the high level of the liquid;    -   the oven comprises a chimney extending between a first end        communicating with the outside of the evacuation chamber and a        second end coming over the high level of the liquid, this second        end allowing the gases under positive pressure in the enclosure        to escape via the evacuation tube;    -   the oven comprises a first temperature probe to measure the        temperature of the gases issuing from the evacuation aperture,        and a second temperature probe located beneath the low level of        the liquid in the evacuation chamber;    -   the oven comprises a first temperature probe to measure the        temperature of the gases issuing from the evacuation aperture,        and a second temperature probe to measure the temperature of the        gases entering the enclosure via the air inlet;    -   the oven comprises calculating means of calculating the humidity        rates in the oven as a function of the temperatures measured at        the first and second probes.

According to another embodiment of the invention, is an oven for cookingfood, comprising an enclosure for receiving and heating the food in amoist cooking atmosphere.

This oven further comprises:

-   -   a water column, containing a predetermined volume of water and        maintained constant between a maximum level and a low outlet        through which the water flows in the column, and    -   a diffuser designed to receive the water flowing from the low        outlet and to vaporize at least part of this water.

Prior art ovens are known possibly comprising means for the productionof steam, in which water is poured on a heating element. It is usuallywished to have a constant production of steam. The quantity of producedsteam is essentially determined by the water flow rate reaching theheating element. But, flow rate regulators used for this function arenot always reliable and need to be adjusted.

That drawback is mitigated by the embodiment above defined.

Indeed, thanks to these dispositions, the water flow rate is essentiallydetermined at the low outlet of the column by the water height in thecolumn between the maximum level, corresponding for example to anoverflow, and the low outlet. This water height can easily be maintainedconstant, without any particular adjustment. Further, when the pressurein the enclosure increases, for instance because of a steam productionlarger than its suppression, the water flow rate automaticallydecreases, without any feed back control means of the electronic type.This embodiment of the invention provides a simple and reliable meansfor a constant production of steam.

Recourse may optionally also be had to one or more of the followingdispositions:

-   -   the maximum level corresponds to an overflow outlet;    -   the water column is located outside the enclosure and the        diffuser is located in the enclosure;    -   the diffuser is an electric heating device; it is the case in        particular when, for instance, the water is vaporized by a        heating resistor;    -   the diffuser is heated by the heat produced by a gas burner;    -   the diffuser rotates about a rotation axis of a fan designed to        stir, inside the enclosure, the steam produced by the diffuser,        this fan creating an area of low pressure in the enclosure;    -   the diffuser is a disk rotating about the rotation axis;    -   the oven comprises an air inlet in the enclosure, located        approximately in the area of low pressure of the fan;    -   the oven comprises a regulation chamber, communicating with the        air inlet of the enclosure, filled at least in part with water        deriving from an overflow of the column, the volume of which is        adjusted so as to vary between a high level and a low level;    -   the oven comprises an admission duct which extends between a        high end and a low end, the high end opening outside the        regulation chamber and the enclosure, and the low end being        covered by water, when the level of the water corresponds        approximately to its high level;    -   the oven comprises an evacuation chamber, filled at least in        part with water deriving from an overflow of the column, the        volume of which is adjusted so as to vary between the high level        and the low level, this evacuation chamber communicating with        the regulation chamber;    -   the oven comprises an evacuation tube extending between the        enclosure, with which it communicates, and a high end opening        into the evacuation chamber above the high level of the water;    -   the oven comprises a chimney extending between a first end        communicating with the outside of the evacuation chamber and a        second end entering above the high level of the water, this        second end allowing the gas under overpressure in the enclosure        to escape via the evacuation tube;    -   the oven comprises a regulation box, itself comprising the        regulation chamber and the evacuation chamber, these two        chambers constituting volumes which are at least partially        separated from one another, communicating between one another by        means of a narrow passage, designed such as to allow the liquid        to circulate between these chambers;    -   the oven comprises, between the maximum level of water in the        column and the low outlet, a cooling circuit extending to the        level of at least a part of the roof, in such a way as to cool        the latter at least partially, and to favour the condensation        above the food of at least a part of the water vapour contained        in the moist atmosphere of the enclosure; and    -   the maximum level and the low outlet feature a difference in        height corresponding to a water pressure at the low outlet of        between 5 and 30 mbar.

According to another embodiment of the invention, is an oven for cookingfood, comprising:

-   -   an enclosure for receiving and heating the food in a moist        cooking atmosphere, this enclosure comprising a top wall        arranged above the food which is to be heated,    -   a heater device arranged in the interior of the enclosure, and    -   a fan, likewise arranged inside the enclosure, this fan        comprising at least one rotating blade, rotating about a        rotation axis on a circular trajectory in order to stir the        cooking atmosphere heated by the heater device.

This oven further comprises:

-   -   a diffuser disk, located in the enclosure, rotating on the        rotation axis integrally with the fan, and    -   a water supply, conducting water from the outside of the        enclosure to the vicinity of the diffuser disk, in such a way        that the water falls onto the diffuser disk and is at least in        part evaporated thanks to the heat produced by the heater        device.

Prior art ovens are known which are provided with a boiler as a steamgenerator, this boiler being usually situated outside the enclosure. Thesteam arrives in the enclosure by a hole. The fan distributes the steamin the enclosure.

This kind of prior art ovens is quite expensive. That drawback ismitigated by the embodiment above defined. Indeed, this disposition issimple and does not require an additional boiler.

Recourse may optionally also be had to one or more of the followingdispositions:

-   -   the diffuser disk is located in the central space located inside        the circular trajectory;    -   the heater is arranged opposite the diffuser disk and heats it,        in order to evaporate at least a part of the water which is        falling onto it;    -   the heater is a gas burner;    -   the water supply comprises a water column, containing a        predetermined volume of water which is maintained constant        between a maximum level and a low outlet through which the water        flows onto the diffuser disk; and    -   the diffuser disk rotates at a speed of rotation adjusted such        that the water falling onto it is at least in part projected        onto the roof.

According to another embodiment of the invention is an oven for cookingfood, comprising:

-   -   an enclosure for receiving the food to be heated, this enclosure        comprising two horizontal walls, respectively forming a bottom        wall and a top wall, connected by at least two vertical side        walls, this enclosure being closed by at least one door which is        also vertical, and    -   a fan arranged in the interior of the enclosure comprising at        least one rotating blade, rotating about a rotation axis on a        circular trajectory.

This oven further comprises:

-   -   a feed system for detergent, conducting the detergent from        outside the enclosure to the vicinity of the fan in such a way        that some detergent falls onto the fan and is projected by the        latter onto each of the walls of the enclosure.

Prior art ovens are known possibly comprising a feed system fordetergent mounted on one of the vertical or horizontal walls of theenclosure. Usually, this feed system is provided on the top wall. But,this type of prior art disposition does not allow projecting thedetergent on all the wall surface of the enclosure.

That drawback is mitigated by the embodiment above defined.

Indeed, thanks to this disposition of the invention, it is possible toproject detergent on all the wall surface of the enclosure because thefan atomizes the detergent and the atomized detergent is drawn by theair flow everywhere in the enclosure.

Recourse may optionally also be had to one or more of the followingdispositions:

-   -   the oven comprises a diffuser rotating with the fan about the        rotation axis, the feed system for the detergent conducting        detergent to the diffuser, in such a way that the diffuser,        rotating, projects detergent in the direction of the walls of        the enclosure;    -   the diffuser is a disk of which the axis of circular symmetry        coincides with the rotation axis of the fan;    -   the feed system for the detergent conducts detergent into a        diffuser consisting of a cylinder having a cylindrical wall with        a cylindrical axis of symmetry coinciding with the rotation axis        of the fan, this wall being pierced by orifices designed to        allow detergent to pass radially to the outside of the cylinder,        to the walls of the enclosure;    -   the feed system for the detergent comprises a receptacle        designed for receiving detergent in such a way that some        detergent is diluted with a liquid supplied above the receptacle        and liquid in which the detergent is diluted flows downstream of        the receptacle in the feed system for the detergent.

According to another embodiment of the invention, is an oven for cookingfood, comprising:

-   -   an enclosure for receiving and heating the food in a moist        cooking atmosphere, this enclosure comprising a top wall        arranged above the food to be heated, and    -   means to generate steam in the interior of the enclosure.

This oven further comprises means of cooling the top wall.

Prior art ovens are known possibly comprising a boiler for production ofsteam, this boiler being usually placed outside of the enclosure. Thesteam arises in the enclosure through a hole. The oven draws the steamin the enclosure. But it is frequently observed that even in that case,food such sauces or creams, for instance, shows at the end of thecooking a dried surface or a skin the appearance of which is notsuitable.

That drawback is mitigated by the embodiment above defined.

Indeed, thanks to this disposition, the steam produced by the means togenerate steam condenses on the top wall and droplets fall in the dishesor greases lying under the top wall.

This disposition allows enough to humidify the surface of the food inorder to mitigate the above mentioned drawbacks.

Recourse may optionally also be had to one or more of the followingdispositions:

-   -   the means of cooling consist of a circuit in which a liquid        circulates, this circuit being in thermal contact with the top        wall;    -   the liquid is water, which flows, downstream of the circuit,        through a low outlet onto a diffuser intended to produce vapour        in the enclosure;    -   a water column located upstream of the circuit and containing a        predetermined volume of water maintained constant between the        low outlet and a maximum level;    -   a water column located downstream of the circuit and containing        a predetermined volume of water maintained constant between the        low outlet and a maximum level.

According to another embodiment of the invention, is an oven for cookingfood, comprising:

-   -   an enclosure for receiving and heating the food in a cooking        atmosphere, this enclosure including two horizontal walls        forming, respectively, a bottom wall and a top wall that are        connected by at least two lateral vertical walls and this        enclosure being closed by at least one door;    -   a fan, arranged inside the enclosure on one of the walls of this        enclosure, this fan including at least one blade rotating about        a rotation axis on a circular trajectory in order to stir the        cooking atmosphere; and    -   an air inlet opening out substantially behind the fan, on the        wall of the enclosure on which the fan is mounted.

Further, in this oven each blade is connected to the rotation axis in asuitable manner so that the air from the air inlet penetrates directlyinside the circular trajectory of each blade before being expelled intothe remainder of the volume of the enclosure.

Prior art ovens are known, for instance by the EP-A-733 862 EuropeanPatent document, possibly comprising an enclosure, a fan arranged insidethe enclosure and an air inlet opening out substantially behind the fan.But, in these prior art ovens, the temperature distribution in theenclosure is not optimised.

That drawback is mitigated by the embodiment above defined. Indeed,thanks to its dispositions, the air from the outside of the enclosurecome in the enclosure, from behind the fan, to be directly andimmediately stired by the fan. A more homogeneous temperaturedistribution is thus obtained in the enclosure.

Recourse may optionally also be had to one or more of defineddispositions:

-   -   the blades are connected to the rotation axis by a disk that        includes at least one hole, located on a circular trajectory,        the radius of which is substantially equal to the distance        separating, on the wall of the enclosure on which the fan is        mounted, the rotation axis and the air inlet;    -   the openings corresponding respectively to the air inlet and to        each hole are substantially circular and have identical        diameters;    -   the holes have a diameter substantially equal to 30 mm;    -   the blades consist of planar rectangular lamellae extending in a        plane substantially perpendicular to the disk and passing        through the rotation axis, and each lamella is connected to the        disk by a first edge and by a second edge opposite said first        edge to a circular ring centred on the rotation axis and        extending in a plane parallel to the disk; and    -   the disk includes six holes regularly distributed angularly        about the rotation axis.

According to another embodiment of the invention is an oven for cookingfood, comprising:

-   -   an enclosure for receiving the food to be heated, this enclosure        having two horizontal walls, one forming a bottom wall and the        other forming a top wall, connected by at least two vertical        side walls, this enclosure being closed by at least one door,        also vertical and comprising a window to give the possibility of        seeing into the enclosure, and    -   means generating an acoustic signal to indicate the end of a        heating process.

This oven further comprises illuminating means designed to produce,within the enclosure, light characteristic of the end of the heatingprocess when said heating process is finished.

Prior art ovens are known which are used for instance as institutionalfood service ovens. In institutional food service kitchens, it is oftenthat several ovens are working at almost the same time. That prior artovens are often designed in order to indicate, by means of a sound, thecompletion of a pre-programmed cooking. The sound is an acoustic signalwhich can be emitted at the end of the heating process as well as at theend at a predetermined time period or when a predetermined temperatureor humidity rate is reached, etc. But, when several prior art ovens areworking in a kitchen, it may have difficult to determine from which onethe sound originates.

That drawback is mitigated by the embodiment above defined. Indeed,thanks to these dispositions, an user can be warned of the end of theheating process by an acoustic signal. Consequently, he is free from thetask consisting in watching over the cooking process. He can go about toones business. Nevertheless, when the completion of the cooking processfor which he wants to be aware occurs, the acoustic signal draws itsattention and the light which is distinctive of the oven in which thisend just occurs, provide him visual signal, visible through a window inthe oven door, in order to help him in spotting easily this oven.

Recourse may optionally also be had to one or more of the followingdispositions:

-   -   the characteristic light is a coloured light;    -   the intensity of the light varies back and forth when the said        heating process is over;    -   the illuminating means are mounted on the door;    -   the door has an insulating space at least partially thermally        insulated from the enclosure and in which the illuminating means        are mounted in the insulating space;    -   the insulating space comprises two glazed panels, an inner panel        and an outer panel, the outer panel having a transparent region        facing a transparent region of the inner panel, to form the said        window, and these two panels being housed in a surround in which        the illuminating means are mounted;    -   the back and forth variation in the intensity of the light        consists in a flashing;    -   the oven comprises slideways for arranging trays superposed        heightwise in the oven and in which the illuminating means are        spread out heightwise; and    -   the inner panel forms, facing the enclosure, a smooth wall.

According to another embodiment of the invention is an oven for cookingfood, comprising an enclosure for receiving and heating food, containinga cooking atmosphere and this oven comprising:

-   -   a fan to stir the cooking atmosphere,    -   an electric motor for driving the fan in rotation alternatively        clockwise and anti-clockwise, this motor incorporating a main        winding, and    -   first switching means adapted for reversing the direction of        rotation of the electric motor.

This type of oven is particularly known from U.S. Pat. No. 4,671,250 andEP A 1 107 650.

Most particularly, the document EP A 1 107 650 discloses an example ofsuch an oven, in which the electric motor is supplied with D.C. currentand the first switching means make it possible to reverse the directionof current into the motor. By reversing the direction of current feedingthe motor, the direction of rotation of the turbine is reversed.

With a view of distributing the heat in the best possible way in theovens for cooking food, it is rather frequently a common practice toreverse the direction of rotation of the fan (every other or fourthminute or so). While the direction is being reversed, the heatingprocess must be interrupted in order to prevent the heat from buildingup at the top of the enclosure. The fact of reversing this rotation willslow down the cooking process and it will be desirable to change thedirection of rotation of the fan as quickly as possible.

However, in this type of oven, the reversal of the direction of rotationis thwarted by the inertia of the fan and the low torque of the motorsmounted in these ovens. For lack of a braking system, it takes the wholeunit, i.e including the motor and the fan, a long time to stop and startagain in the opposite direction. Although motors equipped withelectromagnetic brakes are already available on the market, they arecostly and require a high level of maintenance owing to the wear of thebrake shoes.

That drawback is mitigated by an oven, wherein, in addition to theaforesaid features:

-   -   the main winding is supplied with a source of electrical        alternating current having a determined period, and    -   it further comprises second switching means adapted to        disconnect the main winding from the alternating current source,        during a braking phase, in the course of at least part of at        least one of the two alternations of each period of the        electrical alternating current.

Thanks to these measures, the main winding is supplied with a rectifiedcurrent that will slow down the motor. The motor is then stopped morequickly prior to the rotation reversal thereof.

Recourse may optionally be had to one or more of the followingdispositions:

-   -   the second switching means are adapted to disconnect the main        winding from the source of alternating current, during the        braking phase, in the course of the positive alternations or of        the negative alternations of the electrical alternating current;    -   the second switching means are adapted to disconnect the main        winding from the source of alternating current, during the        braking phase, in the course of the negative alternations and        part of the positive alternations of the electrical alternating        current or in the course of the positive alternations and part        of the negative alternations of the electrical alternating        current; in this way, the power required for the motor braking        can thus be graduated;    -   the second switching means are adapted to connect the main        winding to the source of alternating current, during a driving        phase, in the course of the positive alternations and at least        part of the negative alternations of the electrical alternating        current or in the course of the negative alternations and at        least part of the positive alternations of the electrical        alternating current; the speed of the motor can thus possibly be        graduated during its renewed start-up in the reversed direction;    -   the motor incorporates a secondary winding and the first        switching means are adapted to reverse the direction of the        current respectively in the main and secondary windings before        the braking phase; thus, a higher braking efficiency and        therefore a shorter braking time are attained; and    -   the second switching means are adapted to disconnect the main        winding from the source of alternating current, during a rest        time immediately following the braking phase; this measure makes        it possible to prevent the motor from re-starting, after a        stoppage, into the same direction of rotation as before the        braking phase.

According to another aspect, the invention relates to a process forcontrolling the cooking of food in an oven, wherein:

-   -   the cooking atmosphere inside the oven is stirred by means of a        fan driven by an electric motor with a main winding,    -   with the help of first switching means, the direction of        rotation of the electrical motor is reversed in order to drive        the fan in rotation alternatively both in the clockwise and in        the anti-clockwise direction,    -   the main winding is supplied with a source of alternating        current having a pre-defined period, and    -   during a braking phase, the main winding is disconnected from        the source of alternating current, in the course of part of at        least one of the two alternations of each period of the        electrical alternating current.

Recourse may optionally be had to one or more of the followingdispositions:

-   -   during the braking phase, the main winding is disconnected from        the source of alternating current, in the course of the positive        alternations or of the negative alternations of the electrical        alternating current;    -   during the braking phase, the main winding is disconnected to        the source of alternating current, in the course of the negative        alternations and part of the positive alternations of the        electrical alternating current or in the course of the positive        alternations and part of the negative alternations of the        electrical alternating current;    -   during a driving phase, the main winding is connected to the        source of alternating current, in the course of the positive        alternations and at least part of the negative alternations of        the electrical alternating current or in the course of the        negative alternations and at least part of the positive        alternations of the electrical alternating current;    -   the motor incorporates a secondary winding and the direction of        the current is reversed respectively in the main winding and in        a secondary winding prior to the braking phase;    -   during a rest phase immediately following the braking phase, the        main winding is disconnected from the source of alternating        current.

Other aspects, objects, and advantages of the invention appear onreading the description of various embodiments.

The invention will also be better understood from the accompanyingdrawings, in which:

FIG. 1 is a diagrammatic perspective view of a first embodiment of theoven of the invention;

FIG. 2 is a diagram of the FIG. 1 oven in which, specifically, theenclosure of the oven is shown in section on a vertical planeperpendicular to its back wall, intercepting the back wall and theheater device substantially in the middle;

FIG. 3 is a perspective view of the fan of the oven shown in FIGS. 1 and2;

FIG. 4 is a section of the fan shown in FIG. 3;

FIG. 5 is a perspective view of the circuit for cooling the top wall ofthe oven shown in FIGS. 1 and 2;

FIG. 6 is a diagram analogous to FIG. 2 showing a variant of theregulator of the oven shown in FIG. 2;

FIG. 7 is a diagram analogous to FIG. 5 showing in perspective a variantof the cooling circuit for the top wall of the oven shown in FIGS. 2 and5;

FIG. 8 is a diagrammatic view analogous to FIG. 2 showing a secondembodiment of the oven of the invention;

FIG. 9 is a diagrammatic view analogous to those of FIGS. 2 and 8,showing a third embodiment of the oven of the invention;

FIG. 10 is a diagrammatic view similar to those of FIGS. 2, 8, and 9,showing a fourth embodiment of the oven of the invention;

FIG. 11 is a diagrammatic view, analogous to FIG. 2, a part of a variantof the oven of the preceding Figures, showing a receptacle for receivinga detergent product;

FIG. 12 is a diagrammatic view, shown from the front, the detergentreceptacle of FIG. 11;

FIG. 13 is a schematic view in perspective of a variant of the ovenaccording to the invention;

FIG. 14 is a schematic view partially in section of the oven door shownin FIG. 13;

FIG. 15 illustrates, in a view alike FIG. 14, an alternative of the ovenshown in FIGS. 13 and 14;

FIG. 16 shows schematically in section, in a vertical plane normal tothe bottom wall and intersecting this bottom wall substantially in themiddle, an embodiment of the oven in compliance with the presentinvention;

FIG. 17 shows schematically an embodiment of an electrical power circuitof the motors driving the oven fans as shown on FIG. 16;

FIG. 18 shows schematically a period of the current intended for feedingthe primary circuits of the motors driving the oven fans shown on FIG.16, and

FIG. 19 shows a cycle of operation of the first and second switchingmeans suited for controlling the supply of the motors driving the ovenfans as shown on FIG. 16.

In the various figures, elements that are identical or similar aredesignated by the same references.

Four embodiments of the oven of the invention are described below withreference to FIGS. 1 to 10.

In the first embodiment, shown in FIG. 1, the oven 1 of the inventioncomprises an enclosure 2 (or muffle) contained in a casing 3. The casing3 carries means 4 for regulating the temperature in the enclosure 2, andhas a door 5 allowing food that is to be heated and/or cooked to beinserted into the enclosure 2.

The enclosure 2 is substantially in the form of a rectangularparallelepiped having a front face 6 that is opened or closed by thedoor 5, a back wall 7 opposite from the front face 6, two vertical sidewalls 8 between the front face 6 and the back wall 7, together with abottom 9 and a top 10 forming two horizontal walls. All of these wallsare made of sheet metal.

As shown in FIG. 2, the enclosure 2 also includes a heater device 11, afan 12, a protective grid 13, and slideways 14.

The heater device 11 is placed inside the enclosure 2 facing the fan 12.In the present embodiment, it is constituted by a burner for burninggas. It is fed with gas for burning via a duct 15. The burner 11 is litby an electrode 16 powered electrically by a wire 17 penetrating intothe burner 11 via the duct 15. The burner 11 also has a flame monitordevice 16 a, e.g. operating by ionization, connected to a monitoringunit (not shown) by a wire 17 a. The wires 17 and 17 a leave the duct 15via cable glands.

The gas for burning is advantageously a mixture of air and gas. Thismixture is mixed by a mixer 18. Air is fed via a blower 19. Thus, theair/gas mixture reaches the burner 11 at a pressure slightly aboveatmospheric. The supply of gas for burning is governed by electronicmeans (not shown). In the event of the burner 11 being stopped, forexample when a reference temperature is reached, a small positivepressure is maintained by the blower 19 so as to prevent any vapourrising into the mixer 18.

The fan 12 is mounted substantially in the center of the back wall 7. Itis constituted by a disk 20 centered on an axis of rotation 21.

As shown FIG. 3, at the periphery of this disk 20, the fan 12 has aplurality of blades 22 that are uniformly distributed angularly aroundthe axis of rotation 21. By way of example, these blades 22 areconstituted by plane rectangular plates each extending in a planesubstantially perpendicular to the disk 20 and containing the axis ofthe rotation 21. This symmetry about the axis of rotation 21 enables theblades to be rotated clockwise or counterclockwise in equivalent manner.

Each blade 22 is bound, on one hand, to the disk 20 by a first edge 70and, on the other hand, to a crown 71 by a second edge 72. The crown 71is circular in shape, with an external diameter approximately equal tothe one of the disk 20, and is centred on the axis of rotation 21. Thecrown 71 extends in a plane parallel to the disk 20.

As also shown in FIG. 4, the disk 20 is bored with holes 73. These holes73 form approximately circular openings, regularly angularly distributedaround the axis of rotation 21. According to a first example ofembodiment of the fan 12, it has a 350 mm diameter; it comprises twelveblades 22 and six holes of approximately 30 mm diameter distributed on acircle of 220 mm diameter. This diameter corresponds approximately tothe distance, on the back wall 7, between the centre of the axis ofrotation 21 and the air inlet 44. The blades 22 have, for instance, adimension of 30 mm in the direction parallel to the edges 70 and 72 anda dimension of 80 mm in the direction perpendicular to the edges 70 and72. The holes 73 are approximately on the bisector of the angular sectordelimited by two successive blades 22. As an example, for an air inletof 40 mm diameter, the holes 73 have a diameter approximately of 30 mm.

According to another example, the fan 12 differs from the one abovementioned, essentially by the fact that the disk 20 has a 270 mmdiameter.

The fan 12 is rotated about the axis of rotation 21 by a motor 24, e.g.an electric motor. The direction of rotation of the fan 12 isadvantageously reversed periodically. The fan 12 serves to distributeheat throughout the enclosure 2.

When they are rotating, the blades 22 follow a circular path centred onthe axis of rotation 21 and defining a central space 23.

The burner 11 is placed facing the central space 23. A portion of theburner 11 optionally penetrates into the central space 23.

The protective grid 13 extends in a vertical plane facing the disk 20,in front of the burner 11 and the fan 12 as seen from the cooking space25 for receiving the food to be heated and situated between said burner11 and the door 5. The protective grid 13 is optional.

The slideways 14, comprising ten pairs, extend substantiallyhorizontally on the side walls 8. Each side wall 8 carries one of theslideways 14 in each pair. These slideways 14 serve to hold trays 26 onwhich the food for heating and/or cooking is disposed. Advantageously,the bottoms of the trays 26 have perforations 27.

The enclosure 2 communicates with the outside via an exhaust opening 28.This exhaust opening 28 serves to allow the cooking atmosphere containedin the enclosure 2 to escape whenever said atmosphere is at a pressurethat is higher than the pressure outside the enclosure 2. This exhaustopening 28 is situated below the heater device 11. More precisely, theexhaust opening 28 opens out substantially in the low point of thebottom wall 9. In the embodiment described herein, the bottom wall 9comprises faces sloping downwards towards a point situated substantiallyin the middle thereof.

Condensation occurring inside the enclosure 2 flows along the slopingfaces towards the exhaust opening 28, and is taken therefrom to outsidethe enclosure 2. For this purpose, the exhaust opening 28 communicateswith a siphon 29. When the siphon 29 is full, i.e. in its normalcondition of use, the liquid contained in the bottom of the siphon 29prevents cold air from rising into the exhaust opening 28, and thus intothe enclosure 2, thereby contributing to obtaining a temperature insidethe enclosure 2 that is stable and uniform by avoiding introducing coldair through the exhaust opening 28.

Condensation may come from food that is being cooked in the enclosure 2and/or from vapour-producing means 30 suitable for delivering watervapour into the enclosure 2.

In a variant of the present embodiment (not shown), the exhaust opening28 may open out through one of the side walls 8 and/or through the backwall 7 of the enclosure 2. Under such circumstances, condensation isremoved by other means. In yet another variant, the exhaust opening 28is situated at the junction between the bottom wall 9 and one of theside walls 8 or the back wall 7.

In the embodiment of the invention described herein, the oven 1 has aregulator 31. The regulator 31 comprises an evacuation chamber 32 and aregulation chamber 33. The evacuation chamber 32 and the regulationchamber 33 communicate with each other via a narrow passage 51.

The regulator 31 is situated inside the casing 3 behind the back wall 7with which it communicates via an air inlet 44.

The regulator 31 is partially filled with water by means of a water feed34. The water level in the regulator 31 is controlled by a firstoverflow 35 which flows into the siphon 29. Thus, even when condensationis not sufficient to prevent air rising through the siphon 29, thesiphon can be filled directly by the water feed 34 via the firstoverflow 35.

The water level in the regulator 31 can also be controlled by anemptying valve 36. This emptying valve 36 controls the rate at whichwater flows in an emptying duct 37 connecting the bottom of theregulator 31 to the siphon 29.

The volume of water in the regulator 31, and thus in the evacuationchamber 32 varies between a high level corresponding to the height ofthe first overflow 35, and a low level corresponding to the height ofthe junction between the emptying duct 37 and the regulator 31.

An evacuation tube 38 extends between the evacuation opening 28 and ahigh end 39 opening out into the evacuation chamber 32 above the highand low levels of water in the evacuation chamber 32. This evacuationtube 38 opens out between the evacuation opening 28 and the siphon 29.

The evacuation chamber 32 also communicates with a chimney 40. Thischimney 40 extends between a first end 41 situated outside theevacuation chamber 32 and a second end 42 situated above the high waterlevel. When the pressure inside the enclosure 2 increases, the gascontained in the enclosure 2 escapes through the evacuation opening 28and then via the evacuation duct 38 and the chimney 40.

In the present embodiment, the regulation chamber 33 is adjacent to theevacuation chamber 32. The regulation chamber 33 and the evacuationchamber 32 are separated by a partition 43. The partition 43 does notseparate the evacuation chamber 32 and the regulation chamber 33 in acompletely sealed manner. This partition 43 serves to restrict, withoutcompletely preventing, exchanges of gas and water between the twoenclosures 32 and 33 which take place via the narrow passage 51.

The regulation chamber 33 communicates with the enclosure 2 via the airinlet 44 opening out into the enclosure 2 substantially in a suctionzone established by rotation of the fan 12. The regulation chamber 33also communicates with the outside via an admission duct 45 whichenables air to penetrate into the regulation chamber 33, providing thewater level is situated beneath the admission duct 45.

However, in the event of the pressure in the enclosure 2 rising, even ifthe exhaust opening 28 or the evacuation tube 38 is blocked, the burntgas can escape via the admission duct 45 regardless of the water levelbeing anywhere between its high level and its low level in theregulation chamber 33. If the admission duct 45 dips below the level ofthe water in the regulation chamber 33, then the burnt gas can “bubblethrough” and escape. The regulation chamber 33 thus serves not only togovern humidity by allowing cold and drier air to enter via theadmission duct 45, by varying the water level, but it also serves togovern pressure inside the enclosure 2, and it does this without anymechanical system for opening or closing ducts. The regulator 31 thusserves to perform functions that are analogous to those of mechanicalsystems, such as flaps, but it presents the advantage of not beingcapable of becoming clogged and blocked, thereby giving the oven of theinvention a greater degree of safety.

A first temperature probe 46 is placed in the evacuation chamber 32 inorder to measure the temperature of the gas coming from the exhaustopening 28 and conveyed by the evacuation tube 38. A second temperatureprobe 47 is placed in the regulation chamber 33 in order to measure thetemperature of the gas coming into the enclosure 2 via the air inlet 44.The first probe 46 measures a temperature representative of thetemperature of the enclosure 2, given that cold air from outside theenclosure 2 is prevented from rising by the siphon 29. The second probe47 measures a temperature that is representative of the temperature ofthe air arriving via the admission duct 45.

The first and second temperature probes 46 and 47 are connected tocalculation means 48 for determining the relative humidity inside theenclosure 2. The relative humidity inside the enclosure 2 is calculatedby the calculation means 48 in conventional manner, for instance fromthe difference of temperature between the first 46 and second 47 probesand on the basis of prior calibration.

In the present embodiment, the oven of the invention also hasvapour-producing means 30 for supplying steam (water vapour) to theenclosure 2. In the present embodiment, these vapour-producing means 30comprise a water column 49 and a diffuser 50.

The water column 49 comprises a supply of water 52 and a tube 53.

The supply 52 is located outside the enclosure 2. It has a high outlet54 acting as an overflow and corresponding to the highest level of waterin the column 2. The tube 53 allows water to flow from the supply 52 tothe diffuser 50. Water runs out of the tube 53 into the diffuser 50 viaa low outlet 55.

The diffuser 50 is constituted by a disk that rotates together with therotary shaft 21 of the fan 12. This diffuser disk 50 is situated in thecentral space 23 facing the burner 11. The diameter of the diffuser disk50 is substantially equal to the diameter of the burner 11. The burner11 thus heats the disk 50.

Water running from the column 49 to the vicinity of the disk 50 fallsonto it. The disk 50 as heated by the burner then causes a portion ofthis water to vaporize. Another portion of the water is projected by thedisk 50 and is vaporized in the flames of the burner 11. Another portionof the water which is neither vaporized on coming into contact with thedisk 50 nor in the flames of the burner 11 is projected onto the walls7,8, 9, and 10, and in particular onto the top wall 10. The waterprojected onto the top wall 10 can drip onto the top tray and then viathe perforations 27 from tray 26 to tray 26 towards the bottom wall 9where the water is recovered via the exhaust opening 28. This preventsthe formation of a, dried and/or burnt skin on the food placed in thetrays 26.

The proportion of water projected onto the top wall 10 can be controlledby varying the speed of rotation of the diffuser disk 50.

The pressure difference in the water column 49 between the maximum leveland the low outlet 55 lies in the range 5 millibars (mbar) and 30 mbar.So long as the level of water in the column 49 is kept constant, thispressure difference likewise remains constant, except when the pressureincreases inside the enclosure 2. So long as the pressure inside theenclosure 2 remains substantially equal to the pressure outside theenclosure 2, i.e. atmospheric pressure, then the rate at which waterflows through the low outlet 55 is substantially constant. However, ifvapour is produced inside the enclosure 2, then the pressure inside theenclosure 2 increases above the pressure outside the enclosure 2. Thepressure difference between the maximum level and the low outlet 55 thendecreases, and consequently the rate at which water flows out throughthe low outlet 55 also decreases. The water column 49 thus providesautomatic regulation of the rate at which vapour is produced inside theenclosure 2.

The high outlet 54 communicates with the water feed 34. Water flowingvia the high outlet 54 comes into the regulator 31.

As shown in FIG. 5, the tube 53 has a portion between the water supply52 and the low outlet 55 that forms a cooling circuit 56. This coolingcircuit 56 forms a sinuous coil which extends outside the enclosure 2over a portion of the top wall 10, in contact therewith. By way ofexample, the coil fits closely to grooves formed in the sheet metalconstituting the top wall 10 during stamping thereof.

Thus, the top wall 10 is cooled which assists at least a fraction of thewater vapour contained in the atmosphere inside the enclosure 2 tocondense. The water that condenses on the top wall 10 can drip onto thetop tray. Since the bottoms of the trays 26 have perforations 27, thewater then drips from tray to tray towards the bottom wall 9, where thewater is collected in the exhaust opening 28. This serves to prevent adried-out and/or burnt skin forming on the food placed in the trays 26.

Outside periods during which the oven 1 is in use for cooking food, thewater column 49 may be used to convey detergent to the vicinity of thefan 12. When detergent flows out through the low outlet 55, it fallsonto the diffuser disk 50 which, by turning with the fan 12 about theaxis of rotation 21, projects the detergent to the blades 22 of the fan12 which in turn project detergent towards the walls 7, 8, 9, and 10 ofthe enclosure 2 and towards the door 5. Almost the entire surface of thewalls 7, 8, 9, and 10 of the enclosure 2 together with the door 5 isthus covered in detergent. It is possible to optimize the distributionof detergent over the walls 7, 8, 9, and 10, and over the door 5 bycausing the speed of rotation of the disk 50 and the fan 12 to vary.

In a variant shown in FIG. 6, the first probe 46 is placed in theevacuation chamber 32 in the manner described above, but the secondprobe 47 is also placed in the evacuation chamber, in the water beneaththe low level. Thus, the first probe 46 measures a temperaturerepresentative of the temperature inside the enclosure 2 as explainedabove, while the second probe 47 measures a temperature which issubstantially stable and which can be used as a reference temperaturefor determining the relative humidity in the enclosure 2.

In another variant shown in FIG. 7, the cooling circuit 56 is placedupstream from the supply of water 52.

The second embodiment of the oven 1 of the invention is shown in FIG. 8.In this embodiment, the oven 1 of the invention is analogous to thatdescribed as the first embodiment. It differs essentially by the factthat the heater device 11 is constituted by an electric resistanceheater instead of a gas burner. This electric resistance heater 11 issituated substantially in the same place as the gas burner described forthe preceding embodiment. The electric resistance heater 11 may besituated at least in part in the central space 23. It performsessentially the same functions as the gas burner. In particular, itheats the diffuser disk 50.

In a variant, water from the volume 49 flows directly onto the electricresistance heater. (In this case the oven 1 of the invention needs notnecessarily to have a diffuser disk 50.) The steam which is thenproduced is sucked away and distributed within the enclosure by the fan12.

The third embodiment of the oven 1 of the invention is shown in FIG. 9.In this embodiment, the oven 1 of the invention is analogous to thatdescribed as the second embodiment. It differs essentially by the factthat the diffuser disk 50 is replaced by a diffuser cylinder 57, and theheater device 11 is constituted by an electric resistance heater placedas a ring or a crown around the fan 12.

The diffuser cylinder 57 has a cylindrical wall 58 that is circularlysymmetrical about the axis of rotation 21. This wall 58 is made of metaland is pierced by holes 59. One of the two ends of the diffuser cylinder57 is closed by a disk-shaped partition 60 extending perpendicularly tothe axis of rotation 21. The partition 60 is secured to a shaft co-axialwith the axis of rotation 21. It is centred on the axis of rotation 21.The diffuser cylinder 57 thus rotates together with the fan 12. Theother end of the diffuser cylinder 57 is open. The low outlet 55 of thewater column 49 is situated inside the diffuser cylinder 57. Thus, waterflowing from the column 49 is in part sprayed by the rotatingcylindrical wall 58. The sprayed water escapes via the holes 59 in thecylindrical wall 58 and also through the open end of the cylinder 57,after which it is projected towards the blades 22 of the fan 12 andtowards the walls 5, 7, 8, 9, and 10 of the enclosure 2. Water reachingthe top wall 10 drips onto the trays 26, thus serving to prevent foodthat is being cooked and/or heated in the oven 1 from drying out.

Similarly, when the oven 1 is not in use for cooking food, the watercolumn 49 may be used to convey detergent to the vicinity of the fan.Thus, the diffuser cylinder 57 performs essentially the same functionsas the diffuser disk 50 described with reference to the precedingembodiments.

The fourth embodiment of the oven 1 of the invention is shown in FIG.10. In this embodiment, the oven 1 of the invention is analogous to thatdescribed as the second embodiment. It differs therefrom essentially bythe fact that the heater device 11 is placed as a ring around the fan12, as in the third embodiment, and additional heater means 61 areplaced substantially facing the diffuser disk 50 in order to heat it.These additional heater means 61 are constituted by an electricalresistance heater, for example.

The oven of the invention can be the subject of numerous variationswithout going beyond the ambit of the invention.

Thus, in a variant that is not shown, the enclosure 2 has a front faceand a rear face, each of which can be opened or closed by a door. Undersuch circumstances, a fan 12 is mounted, for example, on at least one ofthe side walls 8, and a heater device 11 is placed facing each fan 12.

In another variant of the invention, shown in FIGS. 11 and 12, the ovenaccording to the invention comprises a receptacle 65 for a detergentproduct. More precisely, the receptacle 65 is inserted in the feedsystem for detergent 49, above the burner 11, the fan 12 and theprotective grid 13. Water is supply to the receptacle 65 via the watercolumn 49. The detergent product is diluted in the water and then flowsat least in part, draw stream of the receptacle 65, from the receptacleto the low outlet 55.

The detergent product can be liquid as well as solid. For this lattercase, the detergent product is, for instance, a tablet or a pellet ofcompressed powder.

As shown in FIG. 12, the receptacle 65 is, for instance, essentiallywith a parallelepipedic shape open on a face. This receptacle 65comprises a cavity 66 in which a pellet 67 can be inserted. This cavity66 is adapted to let water flow around the pellet 67 and to allowcollecting the detergent product diluted in the water so that it drainstoward the low outlet 55.

Of course, the receptacle 65 can be used in combination with any of theother features of the invention as well as independently of those.

In other variants, a plurality of fans 12 and a plurality of burners 11are disposed on the same wall.

In another variant, shown in FIGS. 13 to 15, the oven according to theinvention differs essentially from the previous embodiments and variantsby the fact that it comprises means for signalling the end of a heatingprocess.

As shown on FIG. 13, the oven 1 comprises an enclosure 2 contained in acasing 3. This casing 3 carries regulating means 74. The regulatingmeans 74 comprise means for regulating the temperature, and possibly thedegree of moisture in enclosure 2, as well as means generating anacoustic signal to indicate the end of a heating process. The regulatingmeans 74 also control illuminating means 80, 81.

The enclosure 2 is closed by a door 5 intended for inserting the food tobe heated and/or cooked in said enclosure 2.

The oven 2 can be an electrical or gas-fired oven, with in both cases,heating means as above described.

The enclosure 2 comprises supports, such as slideways 14 (see FIG. 14)for trays 26 receiving the food to be heated and/or cooked in the oven1.

As shown on FIG. 14, door 5 is a double-walled door. It comprises twoglazed panels 75, 76, an inner panel 75 and an outer panel 76.

The inner panel 75 closes the front face 6. It is at least partiallytransparent. The region of the inner panel 75 facing the front side 6 isthoroughly even and smooth.

The outer panel 16 makes up the front face of the oven 1. It is possiblyconvex around a vertical axis.

The inner 75 and outer 76 panels are maintained together encased in aframe 77. The frame 77 extends over part of the periphery of the inner75 and outer 76 panels and maintains them spaced apart to define aninsulating space 78. The insulating space 78 at least partiallythermally insulates the enclosure 2 from the surroundings in which theoven 1 is located. A seal 79 provides for the tightness between the sidewalls 8 a, 8 b and the inner panel 75.

The door 5 is mounted rotatively, on one 8 a of the side walls 8 a, 8 b,around a vertical axis by means of hinges 95.

The illuminating means 80, 81 are mounted in the insulating space 78.The illuminating means 80, 81 are for example made up of two verticalrows of lamps. These lamps are distributed heightwise for example insuch a way that each lamp is located so as to correspond to a space ofthe enclosure 2 limited by two consecutive trays 26 or between one ofthese trays 26 and the bottom 9 or the top 10.

According to an alternative shown on FIG. 15, the illuminating means 80are mounted in the frame 77.

The illuminating means 80 can also be mounted on one side only of theoven 1.

According to other alternatives of the invention, a lamp can illuminateseveral levels. For example, in an oven 1 with ten trays 26, three lampsdistributed across the height can prove sufficient.

The illuminating means 80, 81 are supplied in power by a wiring 82running within frame 77 and crossing one 8 a of the side walls 8 a, 8 b.

The outer panel 76 comprises a transparent region 83 facing atransparent region of the inner panel 75 to form a window making itpossible to see into the inside of the enclosure 2. The outer panel 76comprises an opaque area 84; this opaque area 84 can mask theilluminating means 80, 81 when they are mounted in the insulating space78. However, even when the illuminating means 80, 81 are mounted in theframe 77, the outer panel 76 can comprise an opaque area 84. This opaquearea 84 is for example made up of two coating strips 85 that are screenprinted on one of the faces of the outer panel 76. A handle 86 isprovided on the door 5 to open it.

At the end of a predetermined heating process, the control means 74trigger the flashing of the illuminating means 80, 81.

In another variant, shown in FIGS. 16 to 19, the oven according to theinvention differs essentially from the previous embodiments and variantsby the fact that it comprises means for braking and/or driving and/orreversing the rotation of the fan 12.

According to this variant, shown on FIG. 16, the oven 1 according to theinvention comprises an enclosure 2 (or muffle), closed by a door 5intended for the introduction of food to be heated and/or cooked inenclosure 2.

Enclosure 2 has a substantially parallelepiped shape with a back wall 7,opposed to door 5, two vertical side walls, a bottom wall 9 and a topwall 10.

The side walls are adapted to receive twenty trays 26 on which food tobe heated and/or cooked can be accommodated.

On its back wall 7, the oven 1 incorporates two heating devices 11,respectively circular around horizontal axes X and X′ that are normal tothe back wall 7. The heating devices 11 incorporate, in the embodimentpresented herewith, electrical resistors.

Two fans 12 are mounted to be rotating each respectively around the axesX and X′. Each fan 12 consists of a disk 20 centred on one of the axes Xand X′. On the periphery of the disk 20, each fan 12 comprises aplurality of blades 22 regularly and angularly distributed around one ofthe axes X and X′. These blades 22 are for example made up of planerectangular strips or lamellae extending in a plane that issubstantially perpendicular to the disk 20 and going through the axes Xand X′. This symmetry in relation to one axis X or X′ enables the blades22 to rotate clockwise and anti-clockwise in an equivalent manner.

Each blade 22 is connected on the one hand, with the disk 20 by a firstedge 70 and, on the other hand, with a crown 71 by a second edge 72. Thecrown 71 is circular, with an outside diameter that is substantiallyequal to the one of disk 20. It is centred on the corresponding axis Xor X′. It extends in a plane parallel to disk 20.

The disk 20 has a diameter that is substantially smaller than the one ofthe circle on which each heating 8 extends.

Each fan 12 is driven by a motor M or M′ through a shaft 87 extendingaccording to axis X or X′.

Each motor M or M′, is for example a one-phased motor with four poleswith a power of 250 Watts.

As shown on FIG. 17, each motor M or M′ comprises a main winding 78 anda secondary winding 89.

The motors M and M′ are supplied with alternating current from a currentsource 90 via a supply circuit 91.

Condensers 92 make it possible to shift the phase of the secondarywindings 89 in relation to the one-phased motors M and M′. For 250-wattmotors, their value amounts for example to ten microfarads or so.Resistors 93 unload the condensers 92 after the power supply of themotors M and M′ has been cut off for the purpose of a maintenanceoperation if need be. These resistors 93 reach for example 470kilo-ohms.

Each motor M or M′ is controlled by first K1, second K2 and third K3switching means. The first switching means K1 consist for example of anelectromechanical relay. They make it possible to reverse the directionof current in the main winding 88 in relation to the direction ofcurrent in the secondary winding 89.

The second switching means K2 consist for example of an electronic relaypower relay interposed in the supply circuit 91 of the motors M and M′.This relay is of the so-called asynchronous type.

The third switching means K3 consist for example of a relay. This relayserves as interface for the supply circuit 91 of motors M and M′ withthe control electronics (not shown). This relay controls the firstswitching means K1 of each motor M or M′.

The second K2 and third K3 switching means are mounted for example on arelay card 94.

The second switching means K2 are actuated by control electronics fromthe voltage zero (point Z on FIG. 18 which shows the positive P andnegative N alternations of the sine wave current injected into thesupply circuit 91 of the motors M and M′). The voltage zero Z isdetected by the control electronics.

The control electronics actuate the second switching means K2, from thevoltage zero Z, to connect the motors M and M′ with the current source90 only during the positive alternations P and even only part of thesealternations P (hatched areas on FIG. 18) with a view of graduating thepower required for exerting a braking action on the motors M and M′. Inthis manner, the current used for feeding the motors M and M′ during thebraking phases (referred to as F on FIG. 19) is a rectified current.Thanks to this aspect of the present invention, the use of a rectifyingbridge can thus be spared.

Reciprocally, in order to feed the motors M and M′, during the drivingphases E of the motors M and M′, the second switching means K2 can beactuated by the control electronics, still from the voltage zero Z, inorder to connect the motors M and M′ to the current source 90 during allof the positive alternations P and at least part of the negativealternations N, this with a view of graduating the speed of the motors Mand M′.

In order to achieve a better braking efficiency, prior to injecting therectified current with the help of the second switching means K2, thedirection of rotation of the motors M and M′ can be reversed. Thisinversion is carried out by reversing the direction of current in themain winding 88 in relation to the secondary winding 89 of the motors Mand M′ via the first switching means K1.

In order to prevent the motors M and M′ from starting up again followinga braking action, without having changed the direction of rotation, thesecond switching means K2 are reset during a resting phase R, forexample for 2 seconds, at the end of the braking phases F and before thedriving phases E during which the motors M and M′ are started up againat the desired speed.

FIG. 19 shows a cycle of operation of the first K1 and second K2switching means.

The first switching means K1 can assume two configurations symbolized bythe states 0 and 1 on the upper curve of FIG. 19. State 0 corresponds tothe clockwise direction and state 1 to the anti-clockwise direction.

On the lower curve of FIG. 19, state 0 represents the state in which thesecond switching means K2 disconnect the motors M and M′ from thecurrent source 90 and state 1, the state in which the second switchingmeans K2 connect the motors M and M′ to the current source 90 during thewhole of each period T of the cycle of alternating current feeding thesemotors M and M′. An intermediate state between states 0 and 1corresponds to the braking phases F. As indicated above, this state isreached by connecting motors M and M′ to the current source 90 onlyduring part of the positive alternations P via the second switchingmeans K2. This state can assume any value between 0 and 1 in such a wayto graduate the power supplied to the motors M and M′ during the brakingphases F.

It proves of course equivalent to consider the positive alternations orthe negative alternations reciprocally. Thus, when it is written forexample that the second switching means K2 disconnect the motors M andM′ from the current source 90 during part of the positive alternationsP, it might as well been written that the second switching means K2disconnect the motors from the current source 90 during part of thenegative alternations N and so forth.

Of course, any feature of one of the variants or embodiments can becombined with one or several others without going beyond the scope ofthe invention.

1. An oven for cooking food, comprising: an enclosure for receiving thefood to be heated and for containing a cooking atmosphere, the enclosurecomprising bottom wall and a top wall, interconnected by at least twoupright side walls, the enclosure being closed by at least one uprightdoor, and communicating with the outside by way of an evacuationaperture for gases under positive pressure in the enclosure, a firsttemperature probe to measure the temperature of the gases issuing fromthe evacuation aperture; a second temperature probe, external of theenclosure, to measure a reference temperature; and a control forcalculating humidity rates in the oven as a function of temperaturemeasured at the first and second temperature probes.
 2. The ovenaccording to claim 1, comprising: a heater for heating the cookingatmosphere, a fan, located in the interior of the enclosure, to stir thecooking atmosphere heated by the heater, this fan creating an area oflow pressure in the enclosure, and an air inlet opening in theenclosure, approximately in said low-pressure area of the fan.
 3. Theoven according to claim 2, comprising a regulation chamber, at leastpartially filled with a liquid of which the volume is adjusted so as tovary between a high level and a low level, this regulation chambercommunicating with the air inlet.
 4. The oven according to claim 3,comprising an air admission duct which extends between a high end and alow end, the high end opening outside the regulation chamber and theenclosure, and the low end being covered by the liquid when the level ofthe liquid corresponds approximately to its high level.
 5. The ovenaccording to claim 3, comprising an evacuation chamber, at leastpartially filled with a liquid of volume adapted to vary between thehigh level and the low level, the evacuation chamber communicating withthe regulation chamber during oven cooking operations.
 6. The ovenaccording to claim 5, comprising a regulator box, containing both theregulation chamber and the evacuation chamber, these two chambersconstituting volumes which are at least partially separated from oneanother, communicating between one another by means of a narrow passage,adapted to allow liquid to flow between these two chambers.
 7. The ovenaccording to claim 5, comprising an evacuation tube extending betweenthe evacuation aperture and a high end, opening into the evacuationchamber above the high and low levels of the liquid.
 8. The ovenaccording to claim 7, comprising a chimney extending between a first endcommunicating with the outside of the evacuation chamber and a secondend coming over the high level of the liquid, the second end allowingthe gases under positive pressure in the enclosure to escape via theevacuation tube.
 9. The oven according to claim 6, wherein the secondtemperature probe is located beneath the low level of liquid in theregulator box.
 10. The oven according to claim 5, wherein the firsttemperature probe is located above the high level of liquid in theevacuation chamber.
 11. The oven according to claim 1, comprising meansfor the production of steam, arranged to supply steam in the enclosure.12. The oven according to claim 1 wherein the first temperature probe islocated within an evacuation chamber filled at least partially withliquid, the evacuation chamber receiving gases issuing from theevacuation aperture.
 13. The oven according to claim 12 wherein thesecond temperature probe is located within a regulation chamber filledat least partially with liquid.
 14. The oven according to claim 13wherein the evacuation chamber and regulation chamber communicate witheach other via at least one passage.
 15. The oven according to claim 1wherein both the first temperature probe and the second temperatureprobe are located within an evacuation chamber filled at least partiallywith liquid, the evacuation chamber receiving gases issuing from theevacuation aperture.
 16. The oven of claim 15 wherein the firsttemperature probe is above a liquid level of the evacuation chamber andthe second temperature probe is below the liquid level.